Retailers of goods and services typically offer such goods and services for purchase via one or more conventional brick-and-mortar retail stores and/or via one or more Internet-accessible websites, i.e., one or more websites accessible via a global system of interconnected computer networks. It may be desirable for retailers to track via a shopper membership service purchases made by their customers over time and to associate customers within the shopper membership service with their corresponding purchase histories. It may further be desirable to include in such purchase histories subsequent purchases made by customers in a manner that does not require customers to identify to the retailer at the point-of-sale any information that links the customers within the shopper membership service to their corresponding purchase histories.